The present invention relates generally to vacuum bagging, and more particularly to a method and apparatus for vacuum bagging a component without distorting the component or damaging the bag.
Many stationary structures are made from elements which are bonded together. One such structure is a seal support structure of a gas turbine engine. This support structure has annular seals which become worn or damaged, and must be replaced. Adhesives are frequently used to bond replacement seals to the support structure. In some instances, pressure is applied to the seals to hold them in position as the adhesive cures. Several means are available for applying pressure to the seals including vacuum bags, inflatable pressure bladders or expandable mechanical fixtures. Of these alternatives, the latter two are more expensive and require longer lead times to manufacture. Thus, vacuum bags may be preferred. However, some seal support structures have sharp edges which can puncture the vacuum bags. Further, some support structures can be distorted beyond engineering specifications under the loads applied by a vacuum bag as the adhesive cures. One such seal support structure which has sharp edges and can be distorted is illustrated in FIG. 1.
FIG. 1 shows a partially disassembled stationary oil seal assembly of a gas turbine engine which is designated in its entirety by the reference number 10. The assembly 10 includes mating bevel gears 12, 14 mounted in a sump housing formed by two housing components generally designated by 16, 18 having flanges generally designated by 20, 22, respectively, for joining the components with bolts (not shown). As shown in FIG. 1, the flanges 20, 22 extend only partially around a centerline 24 of the respective components 16, 18. The forward component 16 includes a generally cylindrical seal housing 26 connected to the partial flange 20 by a conical section 28 which extends only partially around the centerline 24 of the component. Forward and aft abradable seals 30, 32 are mounted inside the cylindrical seal housing 26 of the component as illustrated in FIG. 2. Over extended use, the seals 30, 32 become worn or damaged and must be replaced by bonding replacement seals to the component 16.
Because the flange 20 extends only partially around the centerline 24 of the component 16 as shown in FIG. 1, the flange has opposing spaced apart ends 34, 36 presenting sharp edges which can puncture a vacuum bag. Further, because the conical section 28 extends only partially around the centerline 24 of the component 16, the flange 20 and/or conical section can be distorted by the vacuum bag causing the repaired component to be out of engineering specifications. Although the illustrated component is a CFM56 gas turbine engine No. 3 bearing stationary oil seal, those skilled in the art will appreciate that the method and apparatus described herein may be applied to other components without departing from the scope of the present invention.
Among the several features of the present invention may be noted the provision of a component having a centerline and a partial flange extending only partially around the centerline and terminating in spaced apart ends of the flange, and a support element releasably attached to the flange and extending between the ends of the flange for bridging the ends of the flange to prevent the ends from puncturing a vacuum bag when installed around the flange and to prevent the vacuum bag from distorting the component.
In another aspect, the present invention includes a method of preparing a gas turbine engine component for vacuum bagging. The method comprises the step of attaching a support element to the flange to bridge the ends of the flange thereby preventing the ends from puncturing the vacuum bag and preventing the vacuum bag from distorting the component.
Other features of the present invention will be in part apparent and in part pointed out hereinafter.